You should be able to swap around the keys with xmodmap if you can't quite do it with setxkbmap. You need the remove Lock modifier for caps lock, as it is a 'special' key.

remove Lock = Caps_Lock

keycode 66 = Escape NoSymbol

keycode 9 = Caps_Lock ISO_Next_Group

You could place the above in your ~/.Xmodmap, which is still read at startup if the correct command is in your ~/.xinitrc, as I explain further in this answer:

• How do I set Xmodmap on login?

However, you cannot easily mix the xmodmap and setxkbmap commands, as the latter cancels out changes made with the former, as we discussed in the comments.

To execute these xmodmap commands in the terminal to test them, you would run, for example,

xmodmap -e "remove Lock = Caps_Lock"

but you would only place remove Lock = Caps_Lock in your ~/.Xmodmap file, as I explain further in my above linked answer.