Dublin scored 73 goals in a four-year spell at the club before moving to United in 1992.
Cambridge sacked Herve Renard on Sunday and now Harwood is keen on approaching Dublin.
"We are in no rush to recruit the right man for the job but if Dion is interested, we would certainly be interested in hearing from him. Dion had a memorable time here and I would certainly not rule out holding an interview with him to see what he has got to say. His appointment would certainly be popular and he would also add valuable experience - and possibly get us a few goals while he is at it."