Use of the Line Following Sensor from last year?

[Thundrio]

We are using a belt to run basketballs up to the shooter part of our robot for this year. We are planning on using the line following sensor from last year to determine when there is a ball in place. Mechanical insists that it is possible (and I think it is too), but I am not sure how to do this exactly.

Any help or ways to get me started would be useful.

TYIA