We present an integrated nanoelectromechanical circuit designed for achieving ultrasensitive displacement detection. It consists of a suspended quantum dot defined in the two-dimensional electron system of an AlGaAs/GaAs heterostructure and a mechanical resonator located in close vicinity. Operation of the individual components is demonstrated: Mechanical as well as transport properties of the resonator and the electron system are specified, respectively. Coulomb blockade in a freely suspended quantum dot is revealed. The data are used to estimate the maximum displacement sensitivity of the device to be 0.029 Å/sqrt(Hz).