A pencil with a rubber band is a perfect alternate for a cappo. Just put the pencil on the fret you want to put cappo at and tie the band right from upper end goes from the back to the lower section of pencil.
Moreover, are capos necessary?
No, a capo is not at all necessary to play in different keys. It might make it easier in certain situations, but you have to consider the disadvantages of using a capo and then decide whether it’s worth it to you. A common alternative to a capo is having your index finger function as a movable nut (grand barre).
Also question is, does a capo make guitar easier? Using a capo will almost always make the chords feel a little easier which will allow you to play more songs and have more fun which will encourage you to practice more. All of which will make you a better player.