Hi @wgtjai. I have discussed the issue with some of the forms team. Currently each submission is assigned a unique submission identifier. If you were to view your forms through https://app.hubspot.com/forms you will see this unique submission id in the url bar
https://app.hubspot.com/forms/{{portalId}}/{{formId}}/submissions/{{submissionId}}
There is also the option of adding a hidden field in the form using the forms api . This has implications for reporting however as this field will not be consumed by the HubSpot platform for reporting.
You can GET details about form submissions by using the forms api also. Currently the formId is not part of the response payload (this is something the forms team are considering adding in the near future)
Can I ask more details about the particular use case? Why is it useful to have a submissionID for form responses?