Paul has said so, and he's not the only one. From May, 2017:Senator Rand Paul, who two weeks ago demanded the White House and intelligence communities provide evidence whether he was under surveillance by the Obama administration, has dropped another bombshell allegation.
Paul now claims he wasn’t the only Senator to be under surveillance by the former administration.
“I know one other senator who’s already confided to me that he was surveilled by the Obama administration, including his phone calls,”
https://thepoliticalinsider.com/rand-paul-obama-spying-multiple-senators/