Facebook tried to use Pegasus Spyware to monitor better their users especially access to the Apple users data and their activities. Facebook filed a lawsuit against the NSO group in the U.S. for hacking its WhatsApp messenger by exploiting the zero-day vulnerability using Pegasus to steal the WhatsApp users data. Facebook removed the Onavo Protect from the App Store and Google Play as well due to the suspect of monitoring the users. Facebook requested to use purported capabilities of Pegasus to monitor the users on Apple devices and was willing to pay for the ability to monitor.”]
Source: https://gbhackers.com/facebook-tried-to-buy-nso-spyware/