This program enables you to inspect macOS installer packages on your computer. The application might prove to be of good use if you download a suspicious installer package on your Mac and wish to know detailed information regarding its origin and contents.
Suspicious Package comes with a user-friendly interface, provides you with a detailed report based on found information, and is free of charge.
All you need to do is to go to File -> Open and import the installer package in question. The utility will immediately start analyzing the file and provide you with the information you need. An important advantage is that it allows you to check out the contents of your installer package files. You can see the files that are being stored in the installer package (click the files to reveal additional info) and use the integrated search utility to easily find the file of your interest.
My only problem with this application is the fact that it supports a small number of macOS versions (10.11+).
So, you should give this program a try if you're not running a machine that has an operating system version older than El Capitan (10.11).