Sending data to a third party app

We have a program where we use a barcode scanner to enter some data. This program is a third party and I have no way of modifying it.

What I want is to record the time and the number we are scanning before it gets sent to the application.

How can I put a program that is waiting for the input from the barcode scanner and after it gets the data and does something with it, it sends it to the main app?

quick note: the barcode scanner works exactly as a keyboard.

Thanks in advance