The primary data sources for reconstructing the geomagnetic field of the past millennia are archeomagnetic and sedimentary paleomagnetic data. Sediment records, in particular, are crucial in extending the temporal and spatial coverage of global geomagnetic field models, especially when archeomagnetic data are sparse. The exact process on how sediment data acquire magnetization including post‐depositional detrital remanent magnetization is still poorly understood. However, it is widely accepted that these effects lead to a smoothing of the magnetic signal and offsets with respect to the sediment age. They impede the direct inclusion of sediment records in global geomagnetic field modeling. As a first step, we model these effects for a single sediment core using a new class of flexible parameterized lock‐in functions. The parameters of the lock‐in function are estimated by the maximum likelihood method using archeomagnetic data as a reference. The effectiveness of the proposed method is evaluated through synthetic tests. Our results demonstrate that the proposed method is capable of estimating the parameters associated with the distortion caused by the lock‐in process. Plain Language Summary Our paper discusses the post‐depositional detrital remanent magnetization (pDRM) process in sediment records and how it affects the magnetization measured in sediment records. When we study the geomagnetic field of the past, we rely on data from archeological and sedimentary sources. However, there is a problem with sediment records called pDRM, which can make the magnetic signal unclear and cause sediment age to be offset. To make the sedimentary data more reliable, we developed a new method to correct the distortion caused by pDRM. Our method involves a new class of flexible parameterized lock‐in functions. Together with archeomagnetic data, we estimate the parameters of the lock‐in functions. Once we have determined the parameters of the lock‐in function, we can use them to correct the distortion caused by pDRM in sedimentary data. We test our method on synthetic data. Our results show that our method is effective in correcting the distortion caused by pDRM and making sedimentary data more reliable for reconstructing the geomagnetic field. Key Points A new class of parameterized lock‐in functions is presented These lock‐in functions are capable of modeling the offset and smoothing associated with the post‐depositional remanent magnetization process The proposed method is evaluated through several synthetic tests