karabiner.json

{
    "description": "Change caps_lock to control if pressed with other keys, to escape if pressed alone.",
    "manipulators": [
        {
            "from": {
                "key_code": "caps_lock",
                "modifiers": { "optional": ["any"] }
            },
            "to": [{ "key_code": "left_control" }],
            "to_if_alone": [{ "key_code": "escape" }],
            "type": "basic"
        }
    ]
}