As mentioned by mibere and jfb, Port 8953 is used by unbound itself as its standard port for remote controlling it via unbound-control. It would not interfere with normal DNS resolution.
You are likely observing port 8953 in your configuraton because you were trying to reproduce For unbound users: add remote control to your configuration - #4 by vitachaos, and unsuccessfully so, judging by your most recent posts.
Users in this forum are ususally more than willing to help, but you're making that all the more difficult if you spread your problems and configurations over several posts. It's hard to get a complete picture that way.
Also, your original question - what port you should use for unbound when working with Pi-hole - has been answered already.
As it is not necessary to enable remote control in order for unbound to cooperate with Pi-hole, I'd recommend to revert your changes, or better: start from a clean slate.
Following the guide I've posted earlier will lead to a working installation within minutes.
For your issues with remote-controlling unbound, I'd recommend continuing the discussion in the related post, or open a new topic altogether.