solemn lark
Normally I can just go to Keyboard settings -> layout tab -> options -> here I can remap Caps Lock as an additional Escape easily.
Under cinnamon wayland (version 6.0.4) this the entire layout tab is not present.
Looking for a workaround if anyone knows of one. (I've spent a few hours googling and trying various things out to no avail)
odd summit
Not sure if it will help, but there are mapping programs that are known to work with Wayland, could try one of them maybe!? "Input Remapper" is one. 
solemn lark
Got a solve working
Installed keyd
https://github.com/rvaiya/keyd
Config /etc/keyd/default.conf
[ids]
*
[main]
capslock = esc
then just restart keyd service
sudo service keyd restart
Note: Effect the linux console (like if you hit ctrl+alt+f1) as well, a plus for me as I like the consistency, not sure if everyone will want that tho
For me this works great, as it's active in lightdm (the login screen) as well