The answer is a resounding YES. It depends what you want to do with it and I go back to the film days well over half a century ago. You can take ‘happy snaps’ through the eyepiece of bright objects but in this case mobile phone cameras where the lens size is comparable in size to the exit pupil of eyepieces, are likely more efficient. If happy snapping, get as close as possible without bumping the eyepiece, but expect that you won’t get a full frame, just like in the attached Moon image using this method.
Now, if you remove both camera lens and eyepiece, with luck you can achieve prime focus and this is where it really gets interesting because you will be using the main mirror of the telescope as your lens. If your telescope can track your target – even for only around 30 seconds, by cranking up to say 2000ISO you can get passable deep sky images, but beware that the optics need to be properly adjusted. I have included an image with a 6″ F5 telescope of the Eta Carina area and you can see how the focus falls away on one side due to poor alignment.
Now I could rabbit on at length, but the question is what you specifically want to do with it so I will leave my comments there. (If you wish, you could visit my account site and check out more images. Virtually all are DSLR images.)