iPhone 6 every charger says accessory not supported. I have used different chargers, different plugs and when I try with my computer it keeps vibrating as if I was pulling in and out the charger and connecting and disconnecting the cable.

If you are using genuine Apple cables during all of these tests, then use a bright flashlight and magnifying glass to check the charging port on the phone for any sign of damage, debris, dust, lint, etc. You can carefully remove any with something like a wooden toothpick and a short blast with a can of compressed air used with computers.

Then make an appointment at the Genius Bar of the nearest Apple Store to have the device examined.

You're welcome.