Give your hand some relief from reaching for Ctrl and take advantage of the close proximity of Caps Lock.

# Note any previous values for xdb-options (most likely none)
gsettings get org.gnome.desktop.input-sources xkb-options

# Set our xkb-options (plus anything from our get, if needed)
gsettings set org.gnome.desktop.input-sources xkb-options "['ctrl:nocaps']"

Now to retrain your brain ;)

Source: https://askubuntu.com/questions/33774/how-do-i-remap-the-caps-lock-and-ctrl-keys