Karabiner-Elements: Ctrl + Left Click to Alt + Left Click

gistfile1.json

{
    "title": "Change Ctrl + Click to Alt + Click",
    "rules": [
        {
            "description": "Ctrl + Left Click to Alt + Left Click",
            "manipulators": [
                {
                    "type": "basic",
                    "from": {
                        "pointing_button": "button1",
                        "modifiers": {
                            "mandatory": [
                                "left_control"
                            ],
                            "optional": [
                                "caps_lock"
                            ]
                        }
                    },
                    "to": [
                        {
                        "pointing_button": "button1",
                            "modifiers": [
                                "left_alt"
                            ]
                        }
                    ]
                }
            ]
        }
    ]
}