Who knows? Certainly his first national security advisor, Michael Flynn, was wiretapped. And Trump's phone call with the president of Mexico was tapped and passed to the media. And probably more that we don't know about. So, when Trump says he was wiretapped, I'm inclined to believe him.
So who dunnit? Again, nobody knows. But loosely speaking, I'd say Obambi did it. Not that I think Obambi himself put on lineman's climbing spikes and went up pole and popped the alligator clips over the right telephone pair. He has a slew of federal employees to do that. And with modern technology you may not have to stir from in front of your computer screen to tap phones and read email. All the 17 Federal intelligence shops worked for him up to the inauguration and perhaps some of them still do. Most federal civil servants are Democrats. It was reported that the rubberstamp FISA court did issue a warrant to wiretap Trump Tower. Media has kinda stopped talking about that, although they haven't claimed it didn't happen, yet.
We did have a couple of Congresscritters claim that they found no evidence of a tap, but they did NOT say it never happened. They just said that they didn't have written evidence in their hands. Doesn't mean it didn't happen.
The newsies love this kind of stuff, it's simple enough that they can understand it. More so than understanding just what the Obamacare replacement bill will actually do. I haven't figured that out yet, and I am smarter than the average newsie. And so they burn up their airtime talking about wiretaps.