Jacques Necker is a former treasurer of France. He was dismissed rather violently. You can find his Echoe during the quest To Les Invalides. On this page of the Steelrising guide, you will learn their location.
The bells of Sainte-Marie
This Echoe is the wheel of a destroyed wagon. Immediately after the section where you have to jump on crates to get over the fence and after the fight with the Master Chef.
You can find this Echoe on the steps of the Saint-Marie church. It is in front of the main entrance.
At some point during the To Les Invalides quest, you will cross a river. Once you are on other side, enter the building. You will reach a square. The last Echoe is in the left corner.