Hello, as stated by @Carlos Solis Salazar , you can move our on-premises Active Directory workloads to Azure using Azure Migrate. Optionally, and for initial or small scale migrations, you can try something approaches like How to migrate Active Directory Domain Controllers to Microsoft Azure Stack, this will create a domain controller in Azure, connect it to your on-premises DC so you can later demote and disconnect the former. Or, Moving on Premise Active Directory to Azure AD which mentions Azure Active Directory Domain Services, a cloud-only light weight/managed replacement of on-premises Active Directory.
For specifics or better tailored suggestions feel free to detail what other workloads (DHCP, IIS, RRAS, RDS, Exchange Server, SQL Server, ADFS, WSUS, etc.) are present in your on-premises Active Directory, it's logical and network structure/configuration, number of member devices, users, groups, OUs, GPOs, schema extensions, etc.
For applications migration, you may want to take a look to Approach 1 and Approach 2 of the Transition to the cloud guide.
Let us know if you need additional assistance. If the answer was helpful, please accept it so that others can find a solution.