The linker error message is pretty clear: It tells that the function which you are calling in feedbackLoop(), Tool::getPose(...), is declared in a header file, but its implementation is not defined.
In tool.cpp you have a typo: It says Toll::getPose instead of Tool::getPose. I wonder why you are getting a linker error, though, as this should already cause an error during compilation because a Tollclass it not declared anywhere. In your CMakeLists.txt, did you forget to add tool.cpp as a source file in the add_executable() / add_library() call?