droid-at-screen is a free Java-based app that displays the content of your phone’s display to your computer’s display, when the phone is connected via a USB cable.
Below is a screen snap shot taken from my computer display. At the upper left is the Droid@Screen application running. Droid@Screen is connected to my Nexus 5 phone.
At right is the display showing on my phone, which has been transferred from the phone to my computer over a USB connection. I’ve circled two user interface items – the magnifying glass icon is used to adjust the display size of the phone’s screen. Since the phone has a 1920×1080 display, the initial image is quite large!
Below that is a camera icon. Click on that to take a snapshot of what is on the screen, and then save the screen image to a local file.
At the lower left is the DroidAtScreen .jar file. This is the Java executable program file. Assuming Java is installed on your system, double click the .jar file to begin running Droid@Screen.