We are having project A in one organization and Project B in another organization in azure devops services.We have to merge two projects into single organization.i.e.we want pr
Fairly certain there is none: https://developercommunity.visualstudio.com/content/problem/340490/how-can-i-migrate-or-merge-projects-between-to-org.html
Although, there exists a bunch of third party tools: https://marketplace.visualstudio.com/items?itemName=nkdagility.vsts-sync-migration
Feedback item: https://developercommunity.visualstudio.com/idea/365365/make-it-possible-to-move-a-team-project-between-te-1.html
There is no such kind of feature at the moment.
A related user voice here:
make it possible to move a Team Project between Team Project Collections
https://developercommunity.visualstudio.com/content/idea/365365/make-it-possible-to-move-a-team-project-between-te-1.html
Any other 3rd party extension or tool will not keep history info. Suggest you use two organization separately to keep history. Or manually merge it without history.