Damp warm pillowcase trick: stick the snake in that and stick it in a small tub; the movement of the snake against the pillowcase will help to maybe remove the cap(s). I don't leave a snake in there for more than ~10-20 minutes. After you can let the snake run through a damp towel (or the pillowcase) and see if that works too if the snake didn't remove it by itself.

For really stubborn eye caps, I wait until I catch the snake going into the next shed. When I see the snake starting to clear up after the blue stage I stick a warm damp towel into the tub and leave it in there with the snake until I get a shed. Eye caps have always came off: the warm damp towel will get the humidity high in the tub and the snake can rub itself against it while shedding.