Karabiner - https://pqrs.org/osx/karabiner/

I have mine mapped to:

* caps (no other key) => esc * caps + home row => corresponding symbol key

Extremely nice for programming when '(' and ')' are on 'L' and ';' keys - directly under my fingers.

I guess there are other ways and tools, I use this:

1. to put Ctrl on CapsLock:

    setxkbmap -option caps:ctrl_modifier

2. to have "dual" CL as described above:

    xcape -e 'Caps_Lock=Escape'

You can use https://github.com/alols/xcape on linux.