Suppose you want to migrate a list from one site collection to another site collection, Export & Import Power Shell
commands can be used.
Do the export of SharePoint list from source site collection"mysite"
Export-SPWeb http://localhost/mysite/ -path ”D:\backup\CustomList.cmp” -ItemUrl /CustomList-IncludeVersions All-IncludeUserSecurity
Do the import of SharePoint list from network location.