How to measure offline conversions with Custom Audiences

Facebook now enables retailers using Custom Audiences to measure offline sales lift from their ads without needing a third-party partner.
By uploading hashed customer data (emails, phone numbers, addresses) and encrypted transaction info, Facebook matches it with its own database to provide aggregate reports comparing purchase behavior of ad viewers vs.
non-viewers.
This allows marketers to analyze campaign effectiveness, allocate budgets more efficiently, and understand the link between Facebook ads and in-store purchases.
Privacy is maintained through data hashing and deletion after analysis.
Retailers can work with their Facebook representative to set up this measurement.