How does the player start sound of violin?

To start playing a note, use the bow so that the hairs brush the string at one point. This can be easier done by pulling with your hand slightly. When the hairs brush a bit of the rosin you put on the bow earlier, they become more sticky. This stickiness is created by electrostatic forces between hair and rosin. That's what allows you to hear a sound.

The more hairs that brush the string, the louder the note. The faster you pull the bow, the higher the note. You control both: how many hairs will touch the string, and how fast you move the bow.