Ubuntu Remap Caps Lock to F12

To remap Caps Lock to F12, go to Ubuntu > Startup Applications > Add > enter the command:

xmodmap -e "keycode 66 = F12"

This will remap caps lock to f12 at every startup.

Also, ensure that the caps lock is does not actually type in all caps:

$ sudo apt-get install -y gnome-tweak-tool

Tweaks > Typing > Caps Lock key behavior :: Caps Lock is disabled