Map caps lock to esc (if tapped) or control (if held down or combined with another key). Use with Karabiner Elements on MacOS

custom-capslock.json

{
    "title": "Change caps_lock to Esc and Control",
    "rules": [
        {
            "description": "Post Esc if Caps is tapped, Control if held.",
            "manipulators": [
                {
                    "type": "basic",
                    "from": {
                        "key_code": "caps_lock",
                        "modifiers": {
                            "optional": [
                                "any"
                            ]
                        }
                    },
                    "to": [
                        {
                            "key_code": "left_control",
                            "lazy": true
                        }
                    ],
                    "to_if_alone": [
                        {
                            "key_code": "escape"
                        }
                    ]
                }
            ]
        }
    ]
}

karabiner-instructions.md

1. Save file to ~/.config/karabiner/assets/complex_modifications/custom-capslock.json
2. In GUI, add rule under complex modifications
3. Change to_if_alone_timeout_milliseconds from 1000 to 500 ms