Put a spyware on my iPhone 6?

Let me explain why I ask this question in the first place. My Supplier gave me an iphone 6 as a gift. I realize that it doesn't have the plastic wrap when I got it. When I look inside, seems like they just want to put a thank you note inside the box before they gave it to me.

Couple days later i sync my new iphone, and start using them the next day. My supplier called and ask how I like my new iphone, seems like they knew I start using them. I called them the day before with my old iphone, and they didn't ask. I thought it was just a coincidence.

Yesterday, I was having lunch at home and they called. I let them go through my voice mail, and going to call them back after lunch. He called to my home and look for me. I never gave him my home number.

I also noticed that he seems to know more about some issues happening inside my company, which I never discuss with him. I always discuss important issues with my employees through phone or in a meeting room, never on a text. I always put my phone on the table when I was in the meeting room.

IIm not sure if it is possible. I just hope someone who has engineering background could give me some clue.
1. Is it possible for someone to put a spyware on my iphone?
2. How expensive would it be to put a spyware on my iphone? I figure if it is very expensive, then most probably I was just me overreacting.
3. If yes, what could I do to deactivate it? Or would anyone like to trade iphone6 with me?

Someone with right knowledge could easily do that. It wouldn't cost anything if the person knew what they were doing. The only way to be sure to get rid of it is to factory reset the phone entirely. I would backup things that you want to save like pictures or whatever.