A growing set of powerful yet easy-to-use screen components are available to Flow users.
I wanted to provide a little documentation for how screen components are added to screens. Once your org is updated to Spring ’18 or later, you’ll find a new Lightning Components choice at the bottom of your list of screen controls in Cloud Flow Designer:
Simply drag the control over to the right and drop it where you want it to go in your screen.
When you click on a Lightning Component screen element on the right, you can give it a title and then you need to select the component you want to use:
Read the documentation for your component to determine which inputs and outputs you should hook up.