迹 is a bound morpheme - it rarely appears alone and is usually part of a compound: 痕迹 (traces), 足迹 (footprints), 奇迹 (miracle), 古迹 (historic site), 事迹 (deeds), 轨迹 (trajectory).
mistakes
The traditional form 跡 has 足 (foot) on the left, reflecting the original meaning of 'footprint.' The simplified form 迹 uses 辶 (movement radical) instead.
辶 is the motion radical 辵 in bottom-left wrap form. It marks 迹 as something left behind by walking - a track or trace produced by feet in motion. Joins 进退追边, the family of movement-and-route characters.
亦 supplies the sound (yì drifted to jì). The same phonetic appears in 迹 (variant of 跡). Originally depicted a person with marks at the armpits; here purely phonetic - the motion radical handles meaning while 亦 carries sound.
