C++ is widely used by over hundreds of thousands of programmers in essentially every application domain you can think of.
C++ is highly used in writing device drivers and some other software that wholly or partially relies on the direct manipulation of hardware under real-time constraints.
C++ is widely used for teaching and research because it is clean enough for the successful teaching of basic concepts.
Also, the users of AppleMacintosh or a PC running Windows have indirectly used C++, this is because the primary user interfaces of these systems are written in C++.
You can also use C++ to create computer programs, such as video games, art applications, and music players.