When I backpack alone, I grow a beard and don't use deodorant. When I backpack with my girlfriend, I shave, wash my face, take cat baths, and wear unscented deodorant. In the past, I have always just broken a piece off of a deodorant stick, put it in a little bag, and applied it with my fingers. I found myself thinking recently, as I wiped deodorant off my fingers, "Wouldn't it be handy to have a tiny deodorant stick, with a cap?"
Just melt a little bit of solid unscented deodorant in the microwave and pour it into an empty chapstick tube. Maybe someone has already invented this.