You could just wait until he has to pee. Then just grab it so it can't go back in.
Sometimes grooming their belly gets them to drop out. My wife has found a spot that she tickles and her boy drops. Our other boy will drop by cleaning out the smegma in the outer area. You could see if you can get a sedative over the counter. When the vet sedates, that causes them to drop out.
There are products out there for sheath cleaning but usually I just use water or just clean it dry with my hand.