Modify request & response captured via proxy

How to I modify the request & response captured in postman proxy before sending the data to the destination?

I tried using pre-request-script on the collection where I’m dumping the captured requests & responses but that seems to trigger only when the request is executed/originated by postman client itself. However, in my case, the request is originated by the app on my mobile device and postman is acting as a proxy.

The other proxy tools, e.g. Charles Proxy, allows us to modify request/response via multiple ways e.g. using breakpoints.

Please help.