New field in Contact table to be populated in Change record

Hi Experts,

We have a change raised from SRC and once the Change is opened. I'm trying to populate a new field from Contacts table to the cm3r table. This would be based from the cm3r requested.by field or the user who raised the change. I was trying to use the cm3r link but still not getting the values. Can you suggest a solution to achieve this? Thank you.