Samsung bigged up its Link to Windows during its Unpacked event a few weeks ago, and while the feature was expected to filter down to some older handsets, an unofficial APK is up for you to download it now.
The feature lets your Galaxy Note 10's DeX mode cast to a Windows PC or Mac, and you can access the feature now, ahead of the Note 10's August 23 launch. Your phone needs to already support DeX, and you can go ahead and download Link to Windows APK from APKMirror.
You also need to download the Your Phone Companion app from the Google Play Store.
Once you've got both,Your Phone Companion will have magically disappeared from the app drawer, but if you navigate back to the Play Store, it'll display as being installed although there won't be an "open" button, so you'll know its worked. Once you've got this far, swipe down on your screen and tap the dots in the upper right, then hit "button order", and all being well you'll see a "Link to Windows" button that you can add to your control centre, log in, and follow the instructions.