The Grizzlies were up 23-11 after back-to-back 3-pointers by Bobby Moorehead and Brandon Gfeller. But North Dakota State closed the first half on a 17-2 run for a 28-25 lead after Montana went scoreless for seven-plus minutes.
Jacobson's five straight points midway through the second half put North Dakota State up 47-32.
Carlin Dupree added 13 points for North Dakota State (3-1), which made 23 of 34 free throws compared to 16 attempts for Montana.
Martin Breunig had 28 points and 12 rebounds for Montana (2-2). He was 12 of 16 from the field, but had five of the Grizzlies' 17 turnovers.