We know that Microsoft collects a lot of diagnostics data from Windows 10 devices. The collected data is used to keep your Windows 10 up-to-date, keep your Windows 10 secure, reliable and performant, and make improvements to the operating system.
What is Windows diagnostics data?
Windows Diagnostics data is nothing but technical data from Windows 10 devices about the device, installed software and how they are performing. Your Windows 10 device’s hardware configuration, apps installed and their usage, reliability information on device drivers are part of this diagnostics data.
It’s important to note that diagnostics data is completely different from functional data. For instance, if an app connects to Microsoft servers and shares your location to get weather information or local news, then it’s functional data. Since we can control functional data by disabling apps or changing app permissions, we are discussing only diagnostics data here.
Coming back to diagnostics data, not everyone is happy with the way Windows 10 is collecting diagnostics data and sending it to Microsoft servers.
Contrary to what most users believe, it seems that Microsoft may not be collecting diagnostics data from all Windows 10 devices. According to this Microsoft page, Microsoft needs diagnostics data from a limited amount of devices to make big improvements to the operating system.
If Microsoft is collecting data from your Windows 10 device, you will see 
icon in the Windows Diagnostics Data Viewer app which it recently released to help users view the data Windows 10 is sending to Microsoft. In addition to that, you will see 
icon next to diagnostics events that are sent to Microsoft.
So, here is how to check if Microsoft is collecting diagnostics data from your Windows 10 device.
Check if Windows 10 is sending diagnostics data to Microsoft
The Diagnostics Data Viewer app is available to 17083 and above builds only. So, make sure that you are running 17083 or above build before proceeding further.
Step 1: Open the Settings app. Navigate to Privacy > Diagnostics & feedback.
Step 2: In the Diagnostics data section, turn on If data viewing is enabled, you can see your diagnostics data option. Click the Diagnostics Data Viewer button to open the app’s page in the Store app. Click the Get button to install the app.
Step 3: Now, click Diagnostics Data Viewer button to open the app.
Step 4: If your Windows 10 device is sending data to Microsoft, you will see icon in the left-pane. Additionally, you will see icon next to events that are sent to Microsoft.
This way you can easily find out if your Windows 10 device is sending diagnostics data to Microsoft.
As said earlier, functional data and diagnostics data are different. This guide will tell you only if Windows 10 is sharing diagnostics data with Microsoft. If you want to avoid sharing functional data, you can modify default privacy settings by navigating to Settings > Privacy.