Remap Caps Lock

Remapping caps lock key to esc (useful if you are a vim user):
Method 1:

# check caps lock and escape keycodes 
$ xev
# xmodmap -e "keycode  = key_to_map"
# in my case Capslock keycode is 66 
$ xmodmap -e "keycode 66 = Escape"

Method 2:
Create a file ~/.Xmodmap with the following content:

! begin ---------------
remove Lock = Caps_Lock  
add Control = Caps_Lock  
keysym Caps_Lock = Escape
! end -----------------

Method 3:
Menu >> Keyboard >> Layout >> Options >> Caps Lock key behaviour

ref:
http://askubuntu.com/questions/24916/how-do-i-remap-certain-keys