Magic Mock function inside a constructor

I am writing a test, where I create a constructor.
This constructor has one parameter, which I pass a Mock inside.
But except for this parameter, there is another function inside of the parameter and I'm not sure how to get the constructor to see it as a Mock.
Here's an easy example:

Class MyClass():
    def __init__(self, var):
        self._var = var
        self._func = func()
        # Other stuff, I actually care about and can easily check **

Now it's easy to handle the var if I pass it as a parameter in the test:

def test_trying_mock(self):
    var = MagicMock()
    object = MyClass(var)

And the var line is handled. How can I make the constructor see func as mock and make it skip it to the part I actually wanna run and check?