A good way to measure small stuff like that is with a ruler and a high resolution digital camera that has a macro focus feature. Take a picture of the ruler and the connector when the ruler is at exactly the same distance from the camera as the end of the connector is, you can then using image editing software, blow it up and count the number of pixels between two edges of the mm side of the ruler and then count the number of pixels the connector is. If you can get a good in focus image you could do 1/100th of a mm or better for resolution.