Kapanen put the Penguins ahead 2-0 at 12:56 of the first period after Jeff Carter opened the scoring at 3:45.
Heinen, who had the secondary assist on each goal, then scored at 15:15 of the second to extend the lead to 4-1. He signed a one-year contract with Pittsburgh on July 29 after he wasn't tendered a qualifying offer by the Anaheim Ducks.
Kris Letang also scored, Carter (one goal, one assist), John Marino (two assists) and Bryan Rust (two assists) each had two points, and Tristan Jarry made 25 saves for the Penguins.
Pius Suter scored a power-play goal for Detroit. Alex Nedeljkovic started and allowed four goals on 23 shots before being replaced after Heinen's goal by Victor Brattstrom, who made eight saves.
Jake Guentzel did not play for the Penguins after testing positive for COVID-19 prior to the game.
