This tool can be used to test the effect of Pegasus on the phone by backing up the data. However, this tool is said to run better on iOS than on Android.
To check Pegasus on your iPhone, you first need to back up your data and download Amnesty's mvt program. But if you are checking on Mac, you need to download Xcode and Python 3.
Only then can MVT be installed on the Mac. You can then scan your device by following the instructions in the program. While the device is being scanned, your phone is backed up by going to Downloads/pegasus.stix2.
However, Amnesty only provides instructions for Mac OS and Linux. For Windows, you need to install Windows SubSister for Linux.
After installing the necessary software, run the MVT program. After running this program, some notifications will appear, which does not mean that your device is under the control of Pegasus.