Custom keyboard layout for GNOME

custom_xkb.desktop

[Desktop Entry]
Name=Keyboard Layout
Type=Application
Exec=sh -c "sleep 10 && [ -f \\$HOME/.Xkeymap ] && xkbcomp \\$HOME/.Xkeymap \\$DISPLAY 2> /dev/null"
Terminal=false
NoDisplay=true
X-GNOME-Autostart-enabled=true

keymap.xkb

xkb_keymap {
    xkb_keycodes  { include "evdev+aliases(qwerty)" };
    xkb_types     { include "complete" };
    xkb_compat    { include "complete" };
    xkb_symbols   { include "pc+us_custom+inet(evdev)" };
};

us_custom

default  partial alphanumeric_keys modifier_keys
xkb_symbols "us_custom" {

    include "us(basic)"

    name[Group1]= "English (custom layout)";
    key.type[Group1]="ONE_LEVEL";

    key  <ESC> { [ Caps_Lock ] };
    key <CAPS> { [ Control_L ] };
    key <LCTL> { [ Escape ] };
};