Mint Linux on MacBook.

.Xmodmap

! Swap Alt and Cmd keys.
keycode 37 = Control_L
keycode 133 = Alt_L Meta_L
keycode 64 = Super_L
keycode 108 = Super_R
keycode 134 = ISO_Level3_Shift Multi_key
keycode 105 = Control_R Multi_key
clear Shift
clear Lock
clear Control
clear Mod1
clear Mod2
clear Mod3
clear Mod4
clear Mod5
add Shift = Shift_L Shift_R
add Lock = Caps_Lock
add Control = Control_L Control_R
add Mod1 = Alt_L 0x007D
add Mod2 = Num_Lock
add Mod4 = Super_L Super_R
add Mod5 = Mode_switch ISO_Level3_Shift ISO_Level3_Shift ISO_Level3_Shift

! Configure '=' key on numpad as '='.
keycode 0x7D = equal

magicmouse.conf

#/etc/modprobe.d/magicmouse.conf
# To adjust the scroll speed of magic mouse.
options hid_magicmouse scroll-speed=45 scroll-acceleration=1

xmodmap

# ~/.config/autostart/xmodmap
# Add this file to $HOME or through "Start" -> "Startup Application"
/usr/bin/xmodmap /home/<username>/.Xmodmap