Not sure this photo is clear enough to tell us much, and there is no writing on the back to tell me the who, when, or where.
He's wearing a forage cap. I associate such caps with the Civil War era, but after looking around the internet I learned that the Union Army used forage caps in one form or other before and after the war. At any rate, I'm fairly certain the forage cap indicates enlisted, but I'm no expert by any stretch of the imagination.
He has a leather gun belt, gun butt forward,...
Uniforms Speak Volumes