Hi,

Its rather simple question, you can fetch it directly from the database table,

attendance_rec = self.env['hr.attendance'].search([])
for rec in attendance_rec:
    print rec.check_in

The search method will return all the records in the attendance table and iterating over the for loop and from the field named check_in you can get the check-in time. The value you will get will be in UTC, you can convert it to the users timezone.

Thanks