Disable caps lock key on X server, edit /etc/X11/xorg.conf
Section "InputDevice"
Driver "keyboard"
Option "XkbRules" [...]
Option "XkbOptions" "ctrl:nocaps"
Disable with command
$ setxkbmap -option "ctrl:nocaps"
Recompile all *.el files, C-x C-e - to execute
(byte-recompile-directory "/home/user/.emacs.d" 0 t)