When I started running, I ran with my phone in my pocket. I used MapMyRun to track my runs, and also listened to music. It worked out fine, because I was running during the winter, so it could easily fit in my bulky pockets. As it got to spring, I had to buy an armband, as my chunky Samsung S5 would bob up and down in my shorts.
Eventually I completely phased out listening to music on my runs and thought that I was committed to running enough to buy a GPS watch. I managed to get a great deal on a Garmin Forerunner 10 GPS watch and have been running ever since with it. I love it because it is simple, it sits nicely on my wrist and tracks my runs.