Getting precise measurement of a complex rod
You need to disasemble the part and measure it with special equipment, a caliper can help but only as reference since the part has an angled shape.

I recommend to use an optical comparator (base shadows) with this you can have X and Y data to calculate the angle and curves. If you want more precise measurements you can try an Optical Measurement Device (based camera), this also can give you Z but X and Y will help you a lot. Both equipments use a system called Quadra Chek many industries has at least one of this to assure his quality due meets all requirements for Ford GDT guides (geometric dimensional tolerances). no matter the manufacturer brand.

I´ve tried to measure with the phone or table application but is hardly to calibrate on each required dimension. I had to buy an optical comparator.