It's the first time in at least half a century that someone other than a Hearst relative or a castle guide was allowed to stay overnight at the castle.
The couple joined eight other people for a swim in the famous pool, cocktails and hors d'oeuvres on the terrace, a billiards game and dinner in a guest house.
The group also got a customized four-hour castle tour.
The two-day extravaganza was part of a Friends of Hearst Castle adventure that the Hagans won in a 2008 eBay auction.
The organization will use the proceeds to maintain the castle and continue to educate the public.