how can i copy just the contacts from phone to computer or thumb drive

One method is to sync them to iCloud via Settings > iCloud > Contacts on and then log in to https://www.icloud.com/ and open the Contacts app there. Then click the gear-shaped icon at the lower left and click Select All and then click the gear icon again and Export vCard.

You can also sync via iTunes: iTunes 12 for Windows: Sync contacts, calendars, and other info with iPod, iPhone, or iPad

See the last sentence of my previous reply.

There are also 3rd party apps in the App Store but I haven't used any of them so can't make a recommendation.

I only know of 3 ways to do that:

1. Sync to iCloud and then export in vCard format (which still leaves the issue of what to do with the vCard file).

2. Sync via iTunes and then export from the contacts (e.g., Outlook) that you synced to.

3. Via 3rd party software -- search the App Store for "contacts export" gives some possibilities that are free. The first one I found was https://itunes.apple.com/us/app/sa-contacts-export-import/id379262343?mt=8 but as I stated in my reply above I can't personally recommend any as I have not used them.

For a time I used DigiDNA's DiskAid (now iMazing), which gave you access to all the contents of the phone, by dissecting the backups made by iTunes. Pictures, text messages, call logs, contacts, you name it. Really good. Sadly, around the time of iOS 8 their bonhomie disappeared and it was made a fully commercial product with no more educational support. I detest such flip-flops and we parted ways.