UWP, XAML - making CheckBox empty

How can I make CheckBox empty? I only need the tick. Now it takes additional empty space, like here:

<CheckBox
Background="Aqua"
Margin="0,0,0,0"/>

(I added color to look how much space this control takes (that empty space causes alligning problems)).

I just need the tick rectangle, I don't want the empty space. How can I achieve that?

Setting Margin to zeros and Content to "" doesn't work.