Swapping control and caps lock on Lubuntu 16.04

First I ran setxkbmap -option ctrl:swapcaps in gnome-terminal, and observed that the keys were switched on my Macbook keyboard.

Now, following an answer on the web whose URL I've lost, I added that line of text to ~/.config/lxsession/Lubuntu/autostart.

Note that the setxkbmap line the worked in Ubuntu 16.04, setxkbmap -option caps:ctrl_modifier, did not work immediately when run in terminal in Lubuntu.