The 38-year-old actress became romantically involved to Pitt, 50, after meeting him on the set of their 2005 hit 'Mr and Mrs Smith', reported People magazine.
"I wrote something a few years ago for Brad and me. Just for fun. Just an independent little art piece. Because we don't get to do those as much as we'd like. But it's something really small and experimental," Jolie said.
The couple's five-year-old daughter Vivienne recently received her first acting credit, starring alongside her mother in 'Maleficent' as the young Princess Aurora.