Where to put chromedriver.exe for release of Selenium WebDriver C#
Copy Chromedriver.exe into your project's solution / project folder. Add it to the project in visual studio. Right click the file and choose properties. Build Action should be set to 'Content'. That will mean when you build/deploy the bin folder will contain a copy of the chromedriver. When you reference the chromedriver.exe directly, you should look for it adjacent to the executable path of your program.
Good source on detecting location of current assembly/executable: How do I get the path of the assembly the code is in?