Nick Merrill snapped the photo Saturday night onboard the campaign plane, where Clinton -- who was raised in the Chicago suburb of Park Ridge -- was handed a phone and watched highlights from the game.
"That look when you cap off a day on the trail by watching the @Cubs cement their trip to the #WorldSeries. #FlyTheW," tweeted Merrill.
The game had just ended as Clinton was boarding a plane in Philadelphia, where she had a rally Saturday night.
ABC News' Josh Haskell contributed to this report.