Linux

I use keyd for software remapping now, and I like it a lot more than xkb's esoteric options. It has functionality for layers like layer:C, where any "passthrough" input will have the defined modifier (or combo like C-S-M), but you can define whatever other bindings inside.

Long story short, I've used it to remap caps, control, shift (with a custom shift layer for some symbols), and meta, with overloads, double tap/hold into layers, oneshots, timeouts, and all sorts of (surprisingly fluid) nonsense. It's so much easier than wading through xkb options for me.

To sidestep the question slightly less, I always got rid of capslock altogether instead of swapping. That still leaves true escape to be hit accidentally, but I think there should be an option to change escape too?

Edit: what I always used was

# make CapsLock behave like Ctrl:
setxkbmap -option ctrl:nocaps

# make short-pressed Ctrl behave like Escape:
xcape -e 'Control_L=Escape'

from here