Hello dear...Commerce and Psychology are two different poles. I am sorry to say but you cannot pursue both simultaneously. You can opt  Psychology in either B.A course or B.Sc Course , depends on College you choose , but you can't pursue psychology in B.Com. in other words you study Commerce in B. com and Psychology In B.A Or B.Sc.  so you have to choose one in which you are more interested.

Good Luck.