15:01:31 # Life Swapping caps and control in X11. The configuration is at /etc/default/keyboard, and both virtual console and X11 use that configuration in Debian. For systemd users, systemd-localed.service can be used to configure using localectl(1) command, and Debian systemd has been patched to update /etc/default/keyboard (managed by keyboard-configuration package). Not sure where I find a documentation for this. systemd for Debian is patched with debian/patches/debian/Use-Debian-specific-config-files.patch to change /etc/X11/xorg.conf.d/00-keyboard.conf to /etc/default/keyboard.
$ sudo localectl set-x11-keymap us pc105 us ctrl:swapcaps $ cat /etc/default/keyboard XKBMODEL=pc105 XKBLAYOUT=us XKBVARIANT=us XKBOPTIONS=ctrl:swapcaps BACKSPACE=guess