If you use Drift for live chat, you can follow the instructions below to have the Userback widget trigger live chat in your website.
How to connect Userback with Drift
Go to your Drift Widget settings, and turn "Drift Widget icon visibility" off.
Go to the widget settings in Userback and add the code below to the Contact Us Link.
Ref: Drift Widget API
Verify it works in your Userback Widget