On all of my computers I use gnome-tweak-tool to remap CAPSLOCK to CTRL. But there are times when I’m working in a virtual machine that doesn’t have that setup so I need to go back to old school methods.
If you’re on a box just run this from any terminal:
setxkbmap -option ctrl:nocaps
That avoids trying to kill a program with C which usually doesn’t work 🙂
zeusville 
On a distro with systemd,
localectl set-x11-keymap us '' '' ctrl:nocapswill make that persistent too.
that’s awesome thanks.