Remap caps-lock to escape and you're good to go! Or remap capslock to control and use Ctrl-[. Or use karabiner and remap capslock to control-when-held and escape-when-pressed-quickly.
; Author: fwompner gmail com
#InstallKeybdHook
SetCapsLockState, alwaysoff
Capslock::
Send {LControl Down}
KeyWait, CapsLock
Send {LControl Up}
if ( A_PriorKey = "CapsLock" )
{
Send {Esc}
}
return