Hi,
I assume, reading your post, that you want to log it on the server side.
This site has a way to do it but I've never tried it. I assume you could also use
rootsh for what you need it. You could also enable bash history (if it's not) and limit the .bash_history file to append mode only so they cannot delete anything from it. That also would give you an idea of what they've done.
Kind regards,
Eric