Evidence is ultimately a set of REASONING(s) that justifies a claim. 

An object, such as a bloody knife, is not evidence. A bloody knife, by itself, is not evidence that the knife-owner committed the murder, even if that knife was found hidden in his bedroom. His housemate, for example, could have hidden the knife there to frame him. In this case, evidence is the REASONING that connects the bloody knife to the suspected murderer. The bloody knife per se is not evidence.

Hence Cambridge Dictionary has appropriately defined evidence as “one or more REASONS for believing that something is or is not true”.