karabiner

✔ ~/.karabiner.d/configuration
14:19 $ cat karabiner.json
{
    "profiles": [
        {
            "name": "Default profile",
            "selected": true,
            "simple_modifications": {
                "caps_lock": "left_control"
            }
        }
    ]
}

Here is my hammerspoon script:

last_mods = {}

ctrl_table = {
    sends_escape = true,
    last_mods = {}
}

control_shift_timer = hs.timer.delayed.new(0.15, function()
    ctrl_table["send_escape"] = false
    -- log.i("timer fired")
    -- control_key_timer:stop()
end
)

control_handler = function(evt)
  local new_mods = evt:getFlags()
  if last_mods["ctrl"] == new_mods["ctrl"] then
      return false
  end
  if not last_mods["ctrl"] then
    -- log.i("control pressed")
    last_mods = new_mods
    ctrl_table["send_escape"] = true
    -- log.i("starting timer")
    control_key_timer:start()
  else
    -- log.i("contrtol released")
    -- log.i(ctrl_table["send_escape"])
    if ctrl_table["send_escape"] then
      -- log.i("send escape key...")
      hs.eventtap.keyStroke({}, "ESCAPE")
    end
    last_mods = new_mods
    control_key_timer:stop()
  end
  return false
end

control_tap = hs.eventtap.new({12}, control_handler)

control_tap:start()