Even better, hyper key: https://brettterpstra.com/2017/06/15/a-hyper-key-with-karabi...
(Functions as ESC if pressed alone, otherwise acts as hyper key which is great to use for keyboard shortcuts)
As a VIM guy myself, this was huge. I never felt like I was missing out having done this.
Remap CapsLock -> Esc
Changed my life.