Whats the passive voice for : Somebody was calling my name when the police stopped me.

Answer

I was being called by somebody when the police stopped me.

Identify the verb and the object in the sentence. A: The verb is 'calling' and the object is 'my name'.
Change the object to subject and the subject to object. A: 'My name' becomes the subject and 'somebody' becomes the object. The new sentence is 'I was being called by somebody when the police stopped me'.