Hi Aruna,
I am a Recruitment Specialist in an MNC in Hyderabad. I can help you in this regard as I also handle ex-employee verification.
What you can do is prepare a format (WORD or EXCEL) mentioning or asking for the following:
1. Previous Employer
2. Contact Person's Name with Designation (could be any co-worker, peer, project manager, HR personnel, or any superior)
3. Contact Details (email address, phone number, or office board number)
Add a statement stating, "This is highly confidential and will be used only when the candidate joins [your company name]."
You can provide this form to the candidate to fill out once they accept the offer made by your company. After the candidate provides this information, you can contact the person provided in the form to inquire or email them accordingly.
I hope this will be helpful for you. Please let me know if you have any confusion.
All the best,
Minakshi