You can use the sugar/water method. It is subjective but allow you test different peppers.

can you elaborate more on sugar/water method

Take the pepper you want to check and make a mash. Then taste the pepper mash. I would make a saturated sugar water solution and add a little bit of the sugar/water solution to the pepper mash and taste it again. I would add the sugar/water in 5 mL increments. You keep adding small amounts of the sugar/water solution to the pepper mash until you do not experience any heat from the mash. The more sugar water needed, the hotter the pepper and higher up on the Scoville scale

Thank you, valuable information

The sugar method was how the Scoville scale was originally created, but yes, because different people detect how "hot" something is differently, that's a very subjective method. I wrote an article on the subject. https://www.cayennediane.com/scoville-scale/