Ferguson was spotted at Lille's Ligue 1 game against Lyon on March 12 and has told a French radio station that he has been scouting the 21-year-old.
Hazard has previously spoken of his interest in joining a range of clubs - with his suitors believed to include Chelsea, Arsenal, Tottenham and Real Madrid.
However, United could be at the front of the queue to sign the forward in the summer, when Hazard has said he will leave Lille.
"I was at the game and watched Hazard, as well as other players," Ferguson told French station Radio RMC. "That's part of my job, looking at good players.
"Hazard is a very good player and has a lot of qualities. He's particularly quick over the first 10 yards."