Compliance Search for OneDrive Online
You can content index files from OneDrive for Business accounts, and then search the content and metadata for eDiscovery requests.
For more information, see Search and Content Indexing for OneDrive for Business.
Compliance Search for SharePoint Online
You can content index files from the SharePoint Online sites, and then search the content and metadata for eDiscovery requests.
For more information, see Search and Content Indexing for SharePoint Online.
Use a Single Index Server for OneDrive and Sensitive Data Governance
You can use your OneDrive for Business index server and its data for sensitive data governance operations. You do not need a separate index server.
For more information, see OneDrive for Business: Installing Index Store, Content Analyzer, and Web Server.