Hammel also slammed an RBI double to right field in the fifth inning that put the Cubs up, 2-0, in what felt like a tight game before a five-run eighth inning.
"I wish it were a warmer night," Hammel said. "I might have got a little more carry out of that."
With the double, Hammel added his name to the list of Cubs pitchers with big hits over the past four games. Jake Arrieta hit a home run on Sunday, and John Lackey hit a two-out RBI single in Wednesday's win.
"We have athletic pitchers who can do those kind of things," manager Joe Maddon said. "I'm just not going to go up there and just concede [at-bats]."
After Addison Russell led off the fifth with a single, Hammel showed bunt but pulled back on a slider outside the zone.
Before the next pitch, Maddon gave Hammel the green light to swing away.
Hammel, who joked he didn't expect to get on base, crushed a fastball into the outfield to score Russell.
"That's the madness that is Joe Maddon," Hammel said.
As for Hammel's performance on the mound, he allowed four hits, struck out three and earned his first win of the season.
Hammel walked four batters, the only downside of his night, but was able to work his way out of multiple jams.
If anything, that might show the benefit of Hammel's offseason work with pitching guru Tom House. Hammel simplified his mechanics, strengthened his body and developed a mind-set he said prevents him from being his own worst enemy.
"I'm staying aggressive and not beating myself up like I was," he said. "As long as I can stay with the thought process that I have right now and continue to execute when I need to, then it'll be good."
This was Hammel's first start at Wrigley Field since he was bounced from Game 4 of the National League Championship Series after 1 1/3 innings. Through two starts this season, he has allowed only one run in 12 innings.
Maddon said the improvement is telling. Hammel didn't just talk about getting better. He went out and made it happen.
"To his credit, look what he's done to his body and the kind of shape he's in," Maddon said. "He's very committed to the season and to his career."
Cody Stavenhagen is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.