I am fortunate to work with folks from around the world. Mostly we communicate via email (God bless the internet).
Oftentimes in the email replies, I am addressed as “Jhon” and I‘m cool with it. I see this mostly coming from the replies de Central and South American countries. I’ve never spoken with many of these people; they only see my name in print and it is spelled as you would expect an American to spell it.
Why this preference to swap the o and h?
Have you checked your own signature? Maybe you mistpyed it.
Possibly it’s in a store somewhere spelled wrongly - My wife gets letters from a company that seems unable to correct her miss-spelled name.
I can’t type for shit. If I’m going to type your name, I Hold down shift with a finger on left hand, then hit “j” with a finger from the right. Then sometimes (I don’t know why) instead of just hitting the “o”, I put a finger from right hand on “o” and a finger from left on “h” and try to click them in the correct order really fast, and sometimes screw up. Then hit the “n”. Maybe others do the same thing as me?
I don’t know, but I’ll note that “ohn” is a very rare sequence in English words. Besides “john” and its compounds, it only occurs in a few other proper names and the rare word “fohn”. I can imagine that to someone not familiar with the name John, it looks equally as odd as Jhon.
This is quite a mystery… especially if your name is Elizabeth.
Perhaps the “Jh” intuitively feels more like “Juan” for Hispanics?
I know that when I’m writing in French, I sometimes mis-spell words to match English spellings or sounds.
Similarly, I’m a Michael, and I see my name misspelled “Micheal” fairly often.
Seems that Jhon is a Spanish variation: Jhon - Wikipedia
Jhon
a sweet, sensitive guy, laughs a lot, has a big heart, is super cute, likes to have fun, usually is caring, a freak in the sheets, plays sports & likes to have a good time
That guy is such a Jhon. He’s so sweet.
Google shows a number of results, mostly from S. America.
I’ve seen the name ‘Jhon’ mainly from people from Cuba and The Phillippines. Why it is spelled that way, I don’t know, but it’s not uncommon in at least some Spanish-speaking countries.
My GF from Monterrey Mexico has spelled it Jhon since I’ve known her. I’ve corrected her a few times at first and then stopped bothering.
Thousands of Gandhis eagerly await an answer to this question.
It’s common to spell it “J’onn” on Mars. 
One who came to mind is MLB player Jhonny Peralta, who is from the Dominican Republic.
It’s actually a fairly common spelling in Latin American countries.
For whatever reason, Spanish speakers seem to find the combination Jh- less weird than -hn, even though neither normally occurs in Spanish. My Germanic surname contains the combination -gehr. English speakers almost always misspell it as -eghr, since the combination -gh is common in English and -hr almost nonexistent.
I lived off and on in Mexico for years. And I’m a John. Yeah, I think a lot of foreign folks – and even some English speakers, especially children* – know that there’s a weird “h” in “John” that doesn’t belong there, so if they’re unsure, they just insert that “h” in one of the possible locations.
As mentioned by others, what was initially a mistake has become an actual “thing” in parts of the Spanish-speaking world, hence the Jhons and Jhonnys out there.
*I actually have an American (then-)child actor’s personalized autograph as a data point.
This completely explains it 
I go by Jon and my old Argentinian gf would call me “Joni.” Same here, it stopped bothering me after a while. Even when the sun poured in like butterscotch and clung to all my senses.
I’m guessing you mean misspelling it -gher rather than -eghr?
The first is more common, but the second also occurs.
I tell people to spell my name the way that looks wrong. If they spell it so it looks right, that’s wrong. 