- caps lock is not very useful
- caps lock changes the keyboard state, which might be undesirable if you want to use in a keyboard macro program such as Autokey which cannot stop Caps lock from changing state
- the venerable VIM extensively uses Esc to change modes, so you would rather have it closeby
Append some code to your ~/.Xmodmap file. It’s executed at the right time at startup by the xmodmap command, so that your modifications take place every time.
echo " ! Swap caps lock and escape remove Lock = Caps_Lock keysym Escape = Caps_Lock keysym Caps_Lock = Escape add Lock = Caps_Lock" >> ~/.Xmodmap