I'm using mouse in my android game using micro USB to USB Female cable using Unity 5.6. I only want to have zoom capability using the scroll wheel and don't want the cursor to be visible in the game.
I tried both ways, only using Cursor.visible = false; and the above mentioned solution. But in both the cases the mouse cursor remains present, while both ways work inside editor none in android, Please guide me if I need something else to do.

We are having this exact same problem. If we cannot figure a proper solution, we'll try KepAmun's workaround.

(Using Unity 5.0.2f1)

You could, of course, just clear the custom cursor before you build for Android each time, but I don't want to have to remember to do that each time I switch between mobile and stand-alone platforms.

Since Cursor.visible = false and Cursor.SetCursor(null... both seems to do nothing on Android, I made a work around; set the custom cursor texture to a single transparent pixel at run time.

Put this in Start() or Awake() of a script attached to a GameObject in your first scene:
if(Application.isMobilePlatform)
{
Cursor.visible = false; // Once Android cursor bug is fixed, you can delete the next 3 lines.
Texture2D cursorTexture = new Texture2D(1, 1);
cursorTexture.SetPixel(0, 0, Color.clear);
Cursor.SetCursor(cursorTexture, Vector2.zero, CursorMode.Auto);
}

(Using Unity 5.0.1f1)