Are there electrical outlet plates or devices that can be put inside the electric box to measure power usage?
Yes, If you Google "Smart outlets" and similar phrases you will find outlet replacement products that can be used to monitor the power usage of individual outlets. 


  With the {proprietary product name}, controlling and monitoring the power usage in your home has never been easier.





  The {other product name} is the first intelligent plug boasting Air technology.
  - Powerful and switchable
  - Integrated temperature sensor
  - In-built energy and power consumption monitor


I'm not mentioning specific product names here because this isn't an advertising forum and because the actual products available depend on where you are and what year you are reading this.

CNet seem to have reviewed some - only a few do energy monitoring, most are smartphone controlled switches.