// Swap the functions of the right Alt key and the right Ctrl key.
partial modifier_keys
xkb_symbols "swap_ralt_rctl" {
    replace key <RALT> { [ Control_R, Control_R ] };
    replace key <RCTL> { [ Alt_R, Meta_R ] };
};

ctrl:swap_ralt_rctl Swap Right Alt key with Right Ctrl key

ctrl:swap_ralt_rctl = +ctrl(swap_ralt_rctl)

sudo apt-get install dconf-tools

['ctrl:swap_latl_lctl','ctrl:swap_ralt_rctl']

dconf write "/org/gnome/desktop/input-sources/xkb-options" "['ctrl:swap_latl_lctl','ctrl:swap_ralt_rctl']"