Hi @KA SAN CHAN ,
Below are two links that have the details for how to migrate VMs to Azure Stack HCI. One is for migrating from an existing cluster to new hardware (i.e. Azure Stack HCI is installed on different physical hardware), and the other is for migrating to the same hardware (i.e. Azure Stack HCI is installed on the same physical hardware as the existing cluster).
https://learn.microsoft.com/en-us/azure-stack/hci/deploy/migrate-cluster-new-hardware
https://learn.microsoft.com/en-us/azure-stack/hci/deploy/migrate-cluster-same-hardware
Hope this helps!
Trent