Thank you, Viral, for posting the question, and Hari, for answering.
Let me just refine what Hari has said:
1. As Hari says, because of 'when', the two actions are simultaneous, and therefore, there's no need for Past Perfect. However, Hari, be careful, we cannot use 'was being' here, because we're using 'be' as a main verb in its actual meaning and in the Active voice So: Somebody WAS here when I WAS at the office.
2. This sentence is correct because 'It looks like ...' is about the present moment, and because there's no reference to a particular past time in the sentence, we can use the Present Perfect.
3. As Hari says, we cannot say 'been being'. Viral, please watch my latest exclusive video lesson called 'When we can use 'being'.
So, the two options are:
It looks like somebody has been in my home.
Somebody was in my home when I was at the office.