If you’re going to add wood to a charcoal fire you’re better off with chunks. It’s hard to keep sawdust burning slowly enough.
Chunks won’t work in the type of smoker that uses a pan on an electric heating element. In this case you really do need chips or sawdust. There just isn’t enough heat in this type of set-up to cause chunks to burn. They might char a little on the bottom, but that would be it. Generally, the lower the temperature of your heat source, the finer the smoking fuel has to be.
BTW, apple wood produces a mild, sweet-flavored smoke. It’s great for fish and poultry. You might find it underwhelming if you use it for smoking pork or beef.