My phone is vibrating normally but not vibrates when call connects.
Open the Phone app > on the top right side is the menu icon (3 dots icon), tap it > Call settings > On my phone (not lenovo) I see there 3 tabs: SIM Card 1, SIM Card 2, and Common. When I tap Common, I see Advanced. Under it are more options, once of which is "Vibrate when outgoing call answered". Please check if you can see something similar on your phone.