PerformanceCounter CPU usage value allways 0

It's explained by the remarks in the NextValue() documentation:

If the calculated value of a counter depends on two counter reads, the first read operation returns 0.0. Resetting the performance counter properties to specify a different counter is equivalent to creating a new performance counter, and the first read operation using the new properties returns 0.0. The recommended delay time between calls to the NextValue method is one second, to allow the counter to perform the next incremental read.

So if you change your code to something like:

while (true)
{
    Console.WriteLine(pc.NextValue());
    Thread.Sleep(1000);
}

... then you'll see appropriate values.