This is documented here:
Deploying Active Directory Federation Services in Azure https://learn.microsoft.com/en-us/windows-server/identity/ad-fs/deployment/how-to-connect-fed-azure-adfs
You will essentially add a new node in Azure IaaS and if your objective is to remove AD FS entirely from on-premises datacenters, the only difference with the published documentation aforementionned is that you would then move the primary roles to the machine in Azure and then procede to remove the on-prem nodes.
Note that if you are using AD FS for Azure AD integration, the recommendation is to move away from AD FS and use cloud-based authentication. If that's you're case, we can also discuss this here.