Input keycode string not working

Hi everyone

Does anyone know how I can refer to the left parenthesis using the string?
I use the following code:

                CodeInput.text = CodeInput.text + ")";

I don’t understand what I do wrong, if I click the parenthesis button it doesn’t do anything.
I looked it up on the internet and only found that I needed to use that string code.

Thanks for all the help in advance.

Use the following code inside the if statement

If (input.GetKeyDown (KeyCode. Which ever key you want))

I found some thing but I am not a expert at c# so I don’t understand it at all but this is the link
URL : Unity - Scripting API: Input.inputString
If you understand it then tell me to.