No evidence? Here is some evidence.
From the Washington Examiner:
There was a succession of two Foreign Intelligence Act Court requests made by the FBI in June and October of 2016. The first FISA request, which named Trump personally, was denied by the court for insufficient probable cause. The second was granted four months later to allow the FBI to examine and investigate members of “US persons in Donald Trump’s campaign with ties to Russia,” after evidence of a server possibly related to the Trump campaign and two banks was presented. With the target being a server, does it matter whether or not Trump was wiretapped, as he stated, or if the spying was done by infiltrating the server to look into emails and documents? Spying is spying.