If you have the Google Assistant installed on your Android phone, just say, “Hey, Google. Lumos,” and it will turn on your phone’s flashlight. Say, “Hey, Google. Nox,” and it will turn the flashlight off. Your friends will either think you’re a wizard, or have you sent away. 
Hey, that’s pretty awesome! Nox will turn it off and silencio will turn off the ringer. I sometimes whisper “alohamora” when I push the unlock on my car keys.
My phone does nothing, but my phone appears to be on its way to avada kedavra.
It works!