The University of Milan is close to Duomo square (metro M1 and M3 Duomo station)
From Malpensa T1 and T2: trains to Centrale or Cadorna (35 min) and then connections with metro M2 and M3 (Centrale) and M1 and M2 (Cadorna).
From Linate: metro M4 to the city center (15 min) and then connection with metro M1 in San Babila station.
From Centrale train station: connections with metro M2 and M3.