mobile keyboard input string

Hello, I’m building my own mobile keyboard (I’m not using default mobile keyboard for android) and I have an issue about that. I want to make a typing game for mobile phones.
Example: On the top of screen ‘‘Apple’’ word is falling down and when you press A from your mobile keyboard, it will destroy ‘‘A’’ from word. The problem is, you can do that on pc with Input.InputString command (Returns the keyboard input entered this frame. (Read Only)) but how can i return a letter on mobile keyboard? Im not using input field, I just want to press letters and it will destroy the word.

Your custom keyboard does work fine? because if you are using one custom made by you, you should be able to look after which key is pressed and then look if it match with your array of char

Any help?