I think this Celestron adaptor from Bintel would likely be the best bet, Celestron NexYZ 3-Axis Universal Smartphone Adapter Celestron site Bintel, $79
I second Jenifur's option, or something similar of course.
I have a cheap one, that holds the phone OK, and attaches to the scope fine, but, getting the object you want to photograph into the cameras view is a pain in the butt!
Also, if your phone doesn't have some sort of pro mode, apparently there are apps that can add the functionality, at least for some phones.