In Azure Devops or Github, both of them use git as their Version Control, so you can have both as separate git remotes.
You could just use some git commands to handle this. Which command please take a look at this blog.
For automated process, then you could use one CI build definition to achieve it. Detail steps as below:
- Create a CI build with a PowerShell or cmd Task;
- Select the VSTS git repo in Get sources step;
- Enable continuous integration andspecify include all branches for
Branch filters:
Two samples for your reference:
How to synchronize VSTS and Github respositories when commits are made
Syncing my Github repo to MS Visual Studio Team Services
Besides, you could also use some 3-rd party extension to handle this, such as this one--Git Tools for Azure DevOps
Azure Pipelines Build and Release extension that helps you synchronise one Git Repository with another.
You can use this extension with any Git repository: TFS, GitHub, Azure DevOps, Git, etc.