sudo vim /etc/default/keyboard
/etc/default/keyboard(変更前)
# KEYBOARD CONFIGURATION FILE
# Consult the keyboard(5) manual page.
XKBMODEL="pc105"
XKBLAYOUT="jp"
XKBVARIANT=""
XKBOPTIONS=""
BACKSPACE="guess"
/etc/default/keyboard(変更後)
# KEYBOARD CONFIGURATION FILE
# Consult the keyboard(5) manual page.
XKBMODEL="pc105"
XKBLAYOUT="jp"
XKBVARIANT=""
XKBOPTIONS="ctrl:nocaps"
BACKSPACE="guess"