Get Material Parameters

if (DynamicMatInstance)
    {
        float Param;
        DynamicMatInstance ->GetScalarParameterValue(FName("MetalParam"), Param);
        //Param contains the scalar value

        FLinearColor OutColor;
        DynamicMatInstance ->GetVectorParameterValue(FName("ColorParam"), OutColor);
        //OutColor contains the vector value
    }