By "physical servers", do you mean not virtualised or that you have 2 ESXi hosts?
If you mean applications/OS running on bare-metal then you would likely want to be performing a P2V migration using a tool such as vCenter Converter:
How is the current storage presented? e.g. as RDMs or as VMFS LUNs?
To migrate the physical hosts it better to use the p2v converter, but if you need to migrate the VMs that are in your failover cluster, you need to try different V2V convertors. Do you want to migrate a full Failover cluster with VMs or only VMs inside it?
Do you want to virtualize these three physical servers? Depending on the applications that run on this WFSC, I recommend to move from Fibre-Channel to iSCSI (supplied by vSAN) and then add new, virtual cluster nodes. Then remove the old physical servers from the WFC. If this is not possible, P2V migrate the cluster nodes after migrating from FC to iSCSI.Best regards