I will spend a day in Cambridge University next week.
I heard the security maynot allow tripod in the campus, including outdoors.
Any advise on to do and not to do?
There is no "campus". There are the colleges, most of which are clustered around the centre of the city. My experience is that you will be prevented from using a tripod within the grounds of any of them; if you smuggle it past the porters at the gate, one of the roving porters will tell you to stop using it; and within the colleges, which are private property, their Word is Law. I've only ever been allowed to use a tripod inside St John's, and even then only because I obtained special permission in advance. There's not likely to be any objection to your using a handheld camera.
You'll be able to use the tripod in public places, such as King's Parade, though.
You may find that some of the colleges are closed to visitors. Sometimes you can ignore those signs and wander quietly through; it depends on which college, exactly what the gate arrangements are and whether you look as if you belong there.
Of the colleges, my favourite is St John's, but I'm biased. King's Chapel is glorious, of course.
Generally, it's a lovely place. I go back as often as I can manage. Have a look at the Cambridge in Colour web site for some ideas of what can really be done there.