The response assumes the application is provided by you and the phone is attached to a Mac that is able to build and run the application on your iPhone/Simulator
Simulator
The "xcrun simctl" command is a great terminal command, introduced with Xcode6
I hope I did not get you wrong. Basically, you can launch your app on the simulator from outside of Xcode.
You should at first get the list fo devices
xcrun simctl list
Then boot your simulator (if its not booted yet)
xcrun simctl boot <deviceudid>
And finally launch your app
xcrun simctl launch booted <com.yourcompany.yourapp>
Real Device
If you want to build and run an application on a real device, you could make use of the terminal command "xcodebuild".
1) Build the app
Here is an introduction of how to build the app: https://developer.apple.com/library/content/technotes/tn2339/_index.html#//apple_ref/doc/uid/DTS40014588-CH1-HOW_DO_I_BUILD_MY_PROJECTS_FROM_THE_COMMAND_LINE_
2) You can at least RUN unit test / ui tests
https://developer.apple.com/library/content/technotes/tn2339/_index.html#//apple_ref/doc/uid/DTS40014588-CH1-HOW_DO_I_RUN_UNIT_TESTS_IN_OS_X_AND_IOS_FROM_THE_COMMAND_LINE_
If you just want your App to start, I am not quite sure whether it would help you.
A possible attempt would be to start the unit tests and immediately kill the "unit test process" on your Mac. This way the app will not be closed, when the unit tests have finished. Its just an attempt, I haven't tried it.