Displacement measurement is a fundamental functionality in modern science and technology. Although there has been remarkable progress in the precision of such measurements with various laser ranging methods^{1,2,3,4,5,6,7,8}, they are incapable of capturing fast and complex mechanical displacements. Here, we have established a displacement measurement method using time-of-flight detection⁹ with femtosecond optical pulses and frequency-locked electrical waveforms. This method uniquely combines ultrafast measurement speed, sub-nanometre precision and non-ambiguity range of more than several millimetres. The achieved performance features unprecedented detection speed and precision. Starting from 24 nm precision for 4 ns acquisition time, the precision can reach 180 pm for 5 ms acquisition time. Using this method, we show real-time detection of single-event, fast and high-dynamic-range mechanical displacements. This capability can lead to the realization of new measurement and analysis platforms for studying broadband, transient and nonlinear mechanical dynamics in real time, which will be useful for directly probing optomechanics¹⁰, the onset of cracks¹¹, dynamic deformations¹², nonlinear vibrations¹³, ultrasonic phenomena¹⁴ and cell-generated forces¹⁵.

位移测量是现代科学技术中的一项基本功能。尽管使用各种激光测距方法^{1,2,3,4,5,6,7,8}在此类测量的精度方面已取得了显着进步，但它们无法捕获快速而复杂的机械位移。在这里，我们建立了使用飞行时间检测的位移测量方法⁹飞秒光脉冲和锁频电波形。这种方法独特地结合了超快的测量速度，亚纳米精度和超过几毫米的无歧义范围。所获得的性能具有前所未有的检测速度和精度。从24 nm精度开始，采集时间为4 ns，在5 ms采集时间内，精度可以达到180 pm。使用这种方法，我们显示了对单事件，快速和高动态范围机械位移的实时检测。这种能力可以导致实现用于实时研究宽带，瞬态和非线性机械动力学的新的测量和分析平台，这对于直接探测光力学¹⁰，裂纹的出现¹¹很有用。，动态变形¹²，非线性振动¹³，超声现象¹⁴和细胞产生的力¹⁵。