Where to show Job work done by unregd job workers in GSTR3B

Not required to show anywhere in GSTR 3B.

Rule 45(3) of the CGST Rules provides that the principal is required to furnish the details of challans in respect of goods send to a job worker or received from a job worker or sent from one job worker or received from a job worker or sent from one job worker to another job worker during a quarter in FORM GST ITC – 04

So, you required to show that details in ITC 04, not in GSTR 3b or 1.