Hi @Anvesh_Gandham and welcome to the forum!
I think there might be some confusion in the wording of your question. When you say “post call”, are you a developer and you’re wanting to do a POST HTTP web call (which is what Bastien was referring to), or are you not a developer and did you mean post-call as in “after I complete a phone call”?
If you’re a developer and you’re referring to a POST HTTP call, we’ll move this thread to the Developers & API section of the forum - and Bastien is exactly right, using the html_notes field and rich text should be your solution.