http://www.howtogeek.com/howto/windows-vista/disable-caps-lock-key-in-windows-vista/
ctrl
How to remap Capslock as Ctrl in XFCE4
Run this command in terminal
/usr/bin/setxkbmap -option 'ctrl:nocaps'
If you want to swap position of Capslock and Ctrl, use this command:
/usr/bin/setxkbmap -option 'ctrl:swapcaps'
You can add this to Session and Startup –> Application Startup (Choose add new and paste above command to the command textbox) in setting of XFCE4 so that this command will be executed in system’s start.
tatung2112 