My cats never got in the crib. Guess it depends on how old they are.

Try an get them something similar for them or a tower, spray it or sprinkle it with cat nip so they are attracted to it an when they try an go to the crib make a noise to discourage them or call them away from it shut the door to the room of you can

Can I ask how do you plan on keeping the cat out.? We wanted a cat but I didn't wanna have that issue