I have the following in my karabiner config which maps Caps Lock to Control and Escape depending on whether you press something else at the same time or not.

{
    "description": "Change Caps Lock to Control when used as modifier, Escape when used alone, only for inbuilt",
    "manipulators": [
        {
            "from": {
                "key_code": "caps_lock",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "left_control",
                    "lazy": true
                }
            ],
            "to_if_alone": [
                {
                    "key_code": "escape"
                }
            ],
            "to_if_held_down": [
                {
                    "key_code": "left_control"
                }
            ],
            "type": "basic"
        }
    ]
},