After installing [Karabiner][1] and giving required permissions, go to "Complex Modifications" tab on the left and click the "Add your own rule" button. Then paste this code:

    {
    "description": "Remap arrow keys to Option+JKLI",
    "manipulators": [
        {
            "from": {
                "key_code": "i",
                "modifiers": {
                    "mandatory": [
                        "option"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "up_arrow"
                }
            ],
            "type": "basic"
        },
        {
            "from": {
                "key_code": "j",
                "modifiers": {
                    "mandatory": [
                        "option"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        },
        {
            "from": {
                "key_code": "k",
                "modifiers": {
                    "mandatory": [
                        "option"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "down_arrow"
                }
            ],
            "type": "basic"
        },
        {
            "from": {
                "key_code": "l",
                "modifiers": {
                    "mandatory": [
                        "option"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "right_arrow"
                }
            ],
            "type": "basic"
        }
    ]
    }

Feel free to change to the keys you want. This remaps the arrow keys to Option+JKLI

  [1]: https://karabiner-elements.pqrs.org/