curl --request GET \
  --url https://api.salescaptain.com/v1/list-custom-field/{custom_field_id} \
  --header 'Authorization: Bearer <token>'

{
  "message": "Custom field fetched successfully!",
  "custom_field": {
    "data": {
      "cf_id": "d4e5f6a7-b8c9-0d1e-2f3a-4b5c6d7e8f9a",
      "cf_name": "industry",
      "cf_label": "Industry",
      "cf_datatype": "text",
      "cf_description": "Customer's industry sector",
      "created_at": "2024-01-10T09:00:00.000Z",
      "updated_at": "2024-01-15T11:30:00.000Z"
    }
  }
}