Paul Manafort was a senior advisor to the Trump campaign and later campaign manager during the Spring and Summer of 2016. He has a record of past involvement in questionable deals in Pakistan and has served as a paid lobbyist to African dictators with terrible human rights records. He has reportedly been under FBI investigation in the past. Most recently, he has been reported as having received multi-milllon dollars of unreported funds for lobbying for the former Ukralnian President as well as having business ties with powerful Ukrainian and Russian businessmen who are friends  of Putin. Thus, it is very possible that he was the object of an FBI wiretap. not for his role in the Trump  campaign but rather as a result of his business activities. However, any conversations with others involved in the Trump campaign might have inadvertently been monitored., even though they were not the targets of the investigation.