Microsoft developed a command line tool called WinAppDeployCmd so you can deploy an Universal Windows app from a Windows 10 machine to any Windows 10 Mobile device via USB or WiFi (since they're on the same subnet). That's a perfect solution if you doesn't have Visual Studio, the app source code or you're under a Hyper-V Virtual Machine.
Visual Studio allows you to directly deploy an app to a windows phone. You need to register your windows phone as a development phone with Microsoft. Once this is done, you could use visual studio to do this for you. Not sure if you can deploy windows 10 apps to your phone at the moment. Try this link and see: -us/library/windows/apps/ff769508%28v=vs.105%29.aspx Remember to Upvote if this helps.
When you use device portal like mentioned in the answers above, some might get the following error"Failed to start deployment. Failure text: Package failed updates, dependency or conflict validation. (0x80073cf3)"
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