Brough joined Barrow, who are managed by United's Football In The Community Officer Lee Turnbull, in April after becoming frustrated by the lack of first team action at Glanford Park.
Turnbull told the North West Evening Mail: "It looks as though Scott Brough has secured a contract with Grimsby.
"I was hopeful that we would have been able to get him on board (at Barrow), but he's a good prospect and Grimsby are a little bit bigger than us."