How do I spy on a method from a sealed library class?

Question

I have an analytics client that has a track method getting invoked when an event is received.

When I go to mock the class I get this:

 Type to mock must be an interface or an abstract or non-sealed class.

Is there any way to spy on and verify parameters passed to a sealed class method?

in JUnit you can more freely do a "spyOn(class.method)..."

How can this be done in C# or with Moq?

Code looks like:

  private readonly TelemetryClient _telemetry;

    public ClassToTest(TelemetryClient telemetry)
    {
        _telemetry = telemetry;
    }

 public async Task ProcessMessageAsync(EventMessage message, CancellationToken cancelToken)
    {
        try
        {
            var serviceNotificationEvent = JsonConvert.DeserializeObject<ServiceNotificationEvent>(message.Value);
            _telemetry.TrackEvent(AnalyticsConstants.EVENT_RECEIVED);

        }
        catch (Exception e)
        {
            _logger.LogError(e, "Error processing event message");
        }
    }

Current Unit test attempt:

    [TestMethod]
    public void Test_ReceivedEventAnalytic()
    {
        Mock<TelemetryClient> _mockTelemetry = new Mock<TelemetryClient>();

        _serviceNotificationProcessor.ProcessMessagesAsync(mockMessageList);
        IDictionary<String, String> matchingMap = new Dictionary<string, string>();
       // build out matchingMap

        _mockTelemetry.Verify(t => t.TrackEvent("seamEventReceived", It.IsAny<IDictionary<string, string>>(), null), Times.Once());
    }