EXCLUSIVE: Lin-Manuel Miranda Dishes on the 'Life-Changing' Day He Found Out He Was Going to Be a Dad

The 'Hamilton' creator opened up to ET about getting the call to work on 'Moana' the same day he found out his wife was pregnant.

Before he ever began rehearsals for Hamilton, Lin-Manuel Miranda was tapped by Disney to write the songs and music for the New Zealand-set animated adventure Moana. But on the day he got the call, landing a high-profile gig with Disney wasn't even the best news the Tony winner had gotten that day.

"Life changed pretty drastically on that day. I actually found out I was going to be a father that morning," Miranda recently told ET's Kevin Frazier at a junket promoting Moana. "My wife was going off on a business trip and I was still asleep, she had to catch an early flight, and she said, 'Hey I think you might be a dad, alright, I'll see you later!' And I was like, 'Great!... What?'"

"I called her when I fully woke up to confirm what she'd said and then I got the call about Disney later that afternoon," he added.

WATCH: Lin-Manuel Miranda Opens Up About Leaving 'Hamilton': 'This Is Not the End of Anything'

The 36-year-old Pulitzer Prize-winning star explained that the offer from Disney came with a plane ticket to New Zealand, where the film's creative department was attending a musical festival featuring local and traditional artists. So he was soon on a flight to New Zealand.

"I'm flying 18 hours and I've got this secret of 'I'm going to be a dad,'" Miranda recalled. "So it was really one of those life changing weeks."

WATCH: Dwayne Johnson Sings a Lin-Manuel Miranda Song in New 'Moana' Sneak Peek

Miranda and his wife, Vanessa Nadal, welcomed their son, Sebastian, in November 2014. Two years after he was born, Moana is going to be the first movie he watches in theaters.

"I don't think this is a movie you can wait till it gets to video [to see]," Miranda explained. "I think the ocean is so incredible and the effects are so incredible, I really want him to see it on the big screen."

Disney's Moana
hits theaters Nov. 23.

WATCH: Meet Disney’s Newest Princess, Moana, and the 14-Year-Old Hawaiian Native Who Plays Her