Manchester United have long been linked with a move for Dybala, who is expected to leave Juventus at the end of the season.
The Argentina international has struggled in Turin ever since Cristiano Ronaldo touched down from Real Madrid back in the summer.
Reports last week claimed that Manchester United had opened talks with Dybala over a sensational move to Old Trafford.
And McGarry, speaking on The Transfer Window podcast, has claimed United have agreed a deal in principle to sign the attacker.
“There have been some reports In Italy that Manchester United have declared an interest in Dybala,” he said.
“However, our sources are telling us and the information we have is that in fact United have agreed in principle to pay the 100m euros (£86m) buyout clause that it would take to get Dybala out of Juventus.