karabiner

esc-caps-toggle.json

{
  "title": "Escape enhancements",
  "rules": [
    {
      "description": "Escape toggles capslock if enabled",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "escape",
            "modifiers": {
              "mandatory": [
                "caps_lock"
              ]
            }
          },

          "to_after_key_up": [
            { "key_code": "caps_lock" },
            { "key_code": "escape"}
          ]
        }
      ]
    }
  ]
}