Affect reflection vector with obstacle movement

I’m starting to develop games and I have a question about vectors.

I’m developing the Pong game. I want to affect ball movement with paddle movement:

  • When the ball bounce in the paddle, it the paddle if moving, its move will affect ball’s bounce angle.

For example, if the ball comes with a pi/4 radians, it will bounce with a pi/4 radians, but if the paddle is moving, the ball will bounce with a different angle.

How to get the reflection vector when the paddle is moving?

When paddle is not moving, I use this formula.