Update contact ID in custom field while creating a contact

Update contact ID in custom field while creating a contact

Hello,
I am trying to update a custom field in Contacts Module itself when a new contact is created. What I want is that whenever a new contact is created, its contact ID should be copied to that Custom Field.

respMap = zoho.crm.getRecordById("Contacts",input.CID); // get the record
paramap = Map(); // create map to update CID
paramap.put("C_ID",CID);
createResp = zoho.crm.updateRecord("Contacts",pId,paramap);
info createResp;

Thank you for your help