Any number of commercial sensors will work. Some of the key things to look for: Sensitivity & linearity, frequency response, and stiffness of the sensor. One key factor many vendors omit is the stiffness of the sensor, as that can induce dynamic disturbances in the machining process (if you're studying cutting forces).
I am not comfortable suggesting brand names in a public forum.
I remember there were plenty methods to measure the cutting force in machining. Dynamometer is only one of them. For more information take a look at the last version of "Fundamentals of Metal Machining and Machine Tools" by Geoffrey Boothroyd. It has one section about measurement of forces.