NOVELTY - The apparatus (10) has a carrier e.g. casing pipe, conveyed through a borehole. Sensors (102, 103) are placed at the carrier, and perform measurements of downhole properties. The sensors are provided with directions of sensitivity. A processor receives the measurements, and corrects one of the measurements using the other measurement to estimate one of the properties. One of the sensors is semi-permeable to a signal emitted by the other sensor for performing the latter measurement, where one of the directions of sensitivity intersects the other direction of sensitivity.    USE - Hybrid sensor apparatus for estimating property e.g. formation property such as resistivity, density such as mud density, gamma radiation, dielectric permittivity, susceptibility, porosity and conductivity, in a borehole penetrating an earth for a hydrocarbon production application, geothermal production application and a carbon dioxide sequestration application. Can also be used for estimating temperature property, mud condition property and borehole wall distance i.e. standoff.    ADVANTAGE - The apparatus allows a sensor to measure property of interest, while another sensor measures the property that is used to increase accuracy of or apply corrections to measurements or determination of the property of interest so as to improve operation of a downhole tool.    DETAILED DESCRIPTION - The carrier is selected from a group consisting of a wireline, slickline, drill string, coiled tubing, casing pipe, wireline logging tool, slickline logging tool, drop shot, bottom-hole-assembly, drill string insert, internal housing and a substrate portion. INDEPENDENT CLAIMS are also included for the following:    (1) a method for estimating property in a borehole penetrating an earth    (2) a non-transitory computer-readable medium comprising a set of instructions for estimating property in a borehole penetrating an earth.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a hybrid sensor.    Hybrid sensor apparatus (10)    Housing (101)    Downhole property measuring sensors (102, 103)