Understanding the magnetism in iron pnictides is one of the most important steps to reveal the mechanism of superconductivity in these novel materials. In the extensively studied 122-type iron pnictides, the total strength of high-energy spin excitations are nearly temperature independent except for the broadening in Q-space but keep as spin-wave-like behavior up to room temperature. Recently, we have successfully grown high quality, centimeter-size single crystals of CaKFe4As4 (Tc = 35 K). This provides us a new opportunity to examine the common features of spin spectrum among iron pnictides. In our previous experiments, three modes of spin resonance with odd and even L-symmetry are found below Tc. Here we propose to measure the temperature dependence of the high energy spin excitations in CaKFe4As4 using the high flux chopper MAPS / MERLIN.