How do i make mobs to only spawn in caves?

There is a more simple alternative to thes procedures:

Add a additionnal condition to entity spawn. To make that, create a procedure in which you add a "Return [...]" block, and in it add either the option A or B, and then set this procedure to "Custom spawning condition" in "Spawning". This will only apply when the mob try to naturaly spawn, and not when you use a spawn egg. I made like this in my own mod and it work greatly.

PS: Sorry for my bad english, I am french. And I don't know how to add screenshots.

*these procedures

yo, does anyone also know how to do the same thing, but if your wearing a helmet you dont burn? i am making a mod and having a hard time with that