Fetch Dynamic Field Current Value

How to get the current value of the dynamic link field (fieldname= party_name)

(Use-Case = In Opportunity Module there are 2 fields,

  1. opportunity_from (options=customer, lead)

When I select the lead option then it will change to Lead or select Customer can change the Customer…

if I select opportunity_from lead & party_name then I wanted to fetch the current value of that party_name field…!!

and the party_name is dynamic link field…!!

I tried a lot of ways to do it but didn’t satisfy…can anyone help me with how I can fetch this current party_name??